DETROIT (AP) Claressa Shields slugged her way through 10 spirited rounds against Hanna Gabriels - then looked ready to fight another opponent right afterward.

Christina Hammer - the unbeaten German who had won the bout immediately before Shields' - made her way into the ring after Shields beat Gabriels in a unanimous decision. That led to a bit of a commotion.

"I don't go over there in Germany and jump in the ring when she wins a world title," Shields said. "She comes over here, she's been to three of my fights, sitting ringside, jumping in the ring. ... I'm out to prove that I'm the greatest woman of all time, and I'm going to do it step by step, round by round."

Before she could focus on a possible fight with Hammer, Shields first had to deal with Gabriels, an experienced fighter from Costa Rica who knocked Shields down in the first round with what looked like a solid right uppercut. The two-time Olympic champion got up off the canvas, and with a partisan crowd at Masonic Temple cheering her on, Shields recovered quickly and remained undefeated .

"I've never been knocked down before," Shields said. "I've never got an 8-count."

Gabriels said she didn't expect to knock Shields down, and she felt the fight was closer than it was scored. The judges gave it to Shields, 97-92, 98-91 and 97-92.

"I don't think I lost for so many points. I don't know if I lost at all," Gabriels said with a laugh. "But I respect the opinion of the judges."

Gabriels seemed pleased with the show she and Shields (6-0) put on. Shields appeared to have the upper hand by the end of the sixth round, but the 23-year-old from Flint had to work hard against Gabriels, and there were plenty of wild exchanges to keep the crowd engaged.

Shields was already a champion at the super middleweight level, and Gabriels (18-2-1) is a champ at 154 pounds. They met in this bout as middleweights, and Shields took the vacant IBF and WBA titles with her win.

Now the talk immediately turns to a possible fight between Shields and Hammer, who defended her WBC and WBO middleweight titles by outpointing Tori Nelson (17-2-3) in a 10-round fight Friday night, right before the Shields-Gabriels fight.

"Hopefully it's next," Shields said. "I don't need no rest."

Hammer (23-0) spoke briefly to reporters after her victory and before Shields' fight. Hammer said if she fights Shields, she'd want it to be at a more neutral site than Detroit. It seems obvious to everyone how big a Hammer-Shields matchup could be.

"Game changer," Hammer said. "I think that will be the biggest fight ever."

Even Gabriels seems intrigued by the possibility.

"Hammer has to work a lot on her condition, because I heard she looked tired a little bit with Tori," Gabriels said. "She will have to work a lot with her conditioning. Her jab is really good, and she can keep people away. I don't know. It's a fight that I would like to see."

Before Hammer and Nelson fought, Umar Salamov (21-1) stopped Brian Howard (13-2) in the ninth round for the IBF North American light heavyweight title.